Flame-retardant polyester

ABSTRACT

Polyester is made flame retardant by incorporating therein certain cyclophosphazene additives in an amount of from about 1 percent to about 20 percent by weight; a preferred range is from 5 to 10 percent.

United States Patent 11 1 Clutter Feb. 11, 1975 [54] FLAME-RETARDANT POLYESTER 3,280,222 10/1966 Kober et a1. 260/927 3,316,330 4/1967 Nichols 260/927 Inventor Raymond Chm", Ashevllle 3,322,859 5/1967 Sherr et a]. 260/893 I l n 3,356,769 12/1967 Allcock 260/927 [73] Asslgnee fi ncorporated Ashe 6 3,392,214 7/1968 Jaszka 260/927 3,450,799 6/1969 Kober et a1. 260/927 [22] Filed: Dec. 7, 1972 3,505,087 4/1970 Godfrey 106/15 3,629,365 12/1971 Gardner.... 260/857 1 1 pp N971 313,051 3,792,117 2/1974 KOlOdChll'l et a1 260/864 Related US. Application Data P E I D Id E C I rzmary xammerona za a [63] (llgigmgiggkodnoilnegart of Ser. No. 254,557, May 18, Assistant Examiner R' A white Attorney, Agent, or FirmFrancis W. Young; Jack H. 52 us. c1. 260/45.9 NP, 260/45.8 R [51] Int. Cl C09k 3/28 [58] Field of Search 260/45.9 w, 551 P, 927 N, 1571 ABSTRACT 260/75 N, 45.9 NP, 75 T; 252/8.1 Polyester is made flame retardant by incorporating therein certain cyclophosphazene additives in an [56] References Cited amount of from about 1 percent to about 20 percent UNITED STATES PATENTS by weight; a preferred range is from 5 to 10 percent. 2,853,517 9/1958 Fitzgerald et a1. 260/551 8 Claims, No Drawings 3,865,783 11 2 FLAME-RETARDANT POLYESTER N The present application is a continuation-inpart of C st-r. No. 254,557, filed May 13, 1972, now abandoned. 6

BACKGROUND OF THE INVENTION It has been known to utilize various phosphorous 11, 3 00 1 containing materials as modifying additives to polyester to render same flame retardant. However, it is essential l0 C H h l d i h h that any such modified polyester, that is to be processed into fiber and/or filament, be acceptably processable as a synthetic fiber or filament through a full Il end use denior range; it must be also readily dyeable by C6H5 C6H6 the conventional dyeing procedures of the trade. Po1y- C H n r H 6 5 6 5 ester staple, filament, yarn, fiber, and sheets thereof, N can be effectively flame retarded in the practice of this invention. P

PRIOR ART C6IIQ/ C H The preparation and characterization of the phosphazene additives and chemistry that can be used or adapted for use in the practice of this invention is pres- D. Octaphenylcyclotetraphosphazene ented in, for example, Chemical and Engineering News, 2 C6H5 C6H5 Apr. 22, 1968, pages 6881 (H. R. Allcock) and U.S. l I PQLNO. 3,304,350. The preparation of certain organo- C H -P= N -PC H phosphorous polymers and their use as flame retarl ll dants is set forth in the following representative prior N N art: U.S. Pat. 2,891,915; 3,193,397; 3,322,850; British l c Pat. No. 1,208,748; the J.A.C.S., v01. 84, page 55 C6H5 N 6H5 (1962); Chemical Reviews, Vol. 62, pages 247-281 3 g CGH5 (1962); the J.A.C.S., V01. 80, page 2116 (1958); and Inorganic Chemistry 3, pages 429 and 594 (1964).

E. Tris( 2,2-dioxybiphenyl)cyclotriphosphazene DESCRIPTION OF THE INVENTION Polyester polymer and copolyesters, as more fully described herein, are made flame retardant by incorpo- 40 rating therein certain phosphazene phenyl and phenoxy I derivatives as hereinafter defined, prior to, for exam- 0 0 pie, conventional melt spinning. These selected additives reflect sufficient thermal stability on use and impart flame retardant properties to polyester polymer in P the practice of this invention.

Specific cyclophosphazene phenyl and phenoxy de- N N rivatives that can be utilized in polyester polymer to im- I part flame retardand properties thereto include the fol- P A. 2,4,6,8-tetraphenyl-2,4,6,8-tetrakis r l (2,2 ,2-trifluoroethoxy )cyclotetraphosphazene C H C H F. 2,4,6,8-tetraphenyl-2,4,6,8-tetraphenoxycyclotet- 6 5 6 5 I l raphosphazene B. Hexaphenoxycyclotriphosphazene H C H 3 G. Octaphenoxycyclotetraphosphazene 006115 oc H 11 04; N IITOC6H5 Any such cyclophosphazene phenyl and phenoxy derivatives such as those specifically set forth above, which derivatives are incorporated into the polyester polymer in an amount from about 1 to about percent by weight, can be substituted in the representative examples that follow to achieve essentially the same results with a minimum of routine experimentation as would be readily undertaken, if necessary, by one skilled in the art.

These particular cyclophosphazene flame retardant additives can be generically defined and characterized as follows: thermal and chemically stable phenyl or phenoxy derivatives of cyclotriand cyclotetraphosphazenes as flame retardant for polyester, said thermal and chemical stability being maintained at temperatures up to about 300 C. Any such cyclophosphazene meeting the preceding definition as interpreted by one skilled in the art would perform in substantially the same manner as those herein specifically exemplified.

The flame retarded polyester or copolyester produced in accordance with this invention can be satisfactorily processed in the trade and, for example, successfully deep dyed by conventional dyeing procedures from an aqueous system without the use of a carrier or with the use of a lesser amount of carrier. The variety of polyester, dyes, or mixtures thereof that can be utilized is wide in scope and depends on processing conditions and desired results, all within the realm of routine experimentation.

1n the practice of the present invention, conventional additives can be incorporated prior to spinning to achieve a desired result; such additives including dyeing additives, antioxidants, stabilizers, delustrants, etc., singularly or in combination.

The flame retardant additive component of the present invention will be preferably incorporated by mixing immediately prior to extrusion or spinning; it can be added, however. at csterinterchange. This control enables the avoidance of the problem resulting when certain such additives, introduced during polymerization, would normally adversely affect the processing of and- /or degrade the resulting polymer. it is submitted that the results achieved represent a significant contribution to the art in providing, for example, synthetic organic polyester filaments that can be readily processed, which filaments are flame retarded and can be subsequently handled within the skill of the art to produce desired dyed fabrics and carpeting. These end use products are flame retardant as more specifically herein described. Staple, film, and sheets of flame retarded polyester can be produced.

The polyesters employed in practicing this invention include those which are well-known in the art as exemplifled by U.S. Pat. Nos. 2,465,319; 2,901,466; 2,744,089; and 3,018,262. It is to be understood that the term polyester includes both homopolyesters and copolyesters.

1n incorporating the flame retardant additive compo nents into the polymer melt immediately prior to spin ning, known means which will achieve a thorough mixing can be utilized. It is essential that moisture be reduced to an absolute minimum in the polymer. the additives separately or at a temperature below the melting point of any one of the components. The time required for effective drying to reduce moisture content can, of course, be routinely determined. Mechanical mixing will normally be utilized followed by spinning to produce flame retarded commercially accepted filaments. Flame retardant polymeric films or sheets can also be produced.

Typical polyesters which can be modified in the practice of the present invention include those set forth in U.S. Pat. Nos. 2,465,319; 2,437,232; 2,739,957; and 2,895,946. Various processes which can be utilized to prepare such polyesters are set forth for example, in U.S. Pat. Nos. 3,433,770 and 3,406,152, the latter patent also disclosing the addition of additives to control pilling.

Copolyester can be prepared from terephthalic acid or an ester forming derivative thereof and a glycol of the formula HO(CH ),,OH, wherein n is an integer of from 2 to about 10, in the presence of a dye sensitizing sulfonate containing compound, a branching agent, such as glycerol, and a dye dispersing and dye retaining aliphatic diacid or ester thereof. The particular copolyester, sulfonate containing additive, branching agent, and aliphatic diacid (or ester thereof) selected singularly or in combination, is not critical.

Polyesters and copolyesters which can be modified in the practice of this invention are well-known in the art and include those of U.S. Pat. No. 3,018,272; this disclosure also sets forth sulfonate group containing compounds which can be utilized in the practice of the present invention. U.S. Pat. No. 3,096,358 sets forth additional sulfonate compounds which can be utilized in conjunction with a selected aliphatic diacid of the formula:

HOOC(CH),,COOH n having a value of from 2 to 18. Preferred species aliphatic diacid additives are the azelate and adipate diacids and ester derivatives thereof.

Branching agnets which can be utilized include hexanetriol; pentaerythritol; trimethylolpropane, sorbitol; trimethylol ethane; glycerol; trimethylol benzene-1 ,3 ,5; tripropylol benzene- 1 ,3 ,5; tributylol benzene-1,3,5; trihexylol benzene-1,2,6; trimethyl trimesate; triethyl trimesate; tripropyl trimesate; tetramethyl pyromelli- 'tate; tetramethyl mellophanate; trimethyl hemimellitate; trimethyl trimellitate and tetramethyl prehnitate.

Examples of sulfonate group containing compounds which can be utilized include metallic salts of sulfomoncarboxylic esters, sulfodicarboxylic esters, monohydric and dihydrocalcohols containing at least one sulfonic acid group and monohydric alcohols containing one carboxylic ester group and at least one sulfonic acid group.

Among the basic and disperse dyestuffs which readily dye the fibers produced from the flame retarded polyester of this invention are the Genacryl and Celliton dyes discussed on pages 432 to 433 of the American Dyestuff Reporter, volume 43, 1954, for example, Genacryl Red 68 (a basic dye of quaternary ammonium type), Genacryl Pink G. (Basic Red 13; Color Index 48015), Genacryl Blue 6G; Celliton Fast Red GOA Ex. Cone (Disperse Red 17; Color lndex No. 11210); Celliton Fast Blue AF Ex. Cone (Color lndex No. 61115); Fuchsine SBP (a basic dye of the triphenylmethane type); Fuchsine Conc. Basic Violet 14 (Color Index No. 12510); Methyl Violet 2B; Brilliant Blue 6G; Methylene Blue SP; Victoria Green WB (Color lndex 657); Victoria Green (Basic Green 4; Color Index No. 42000); Rhodamine B (Color Index 749); Brilliant Green B (Color lndex 662); Sevron Brilliant Red 4G; Maxilon Red BL; Basacryl Blue GL; and the like.

Additional specific dyestuffs which can be utilized include the following:

Dyestuff Color Index Name Sevron Yellow R Astrazon Yellow 7GLL Sevron Orange G Basic Yellow 11. Basic Yellow 21. Basic Orange 21.

Maxilon Red BL Basic Red 22. Astrazon Red BBL Basic Red 23. Astrazon Red RL Basic Red 25. Sevron Red GL Basic Red 18. Sevron Blue ER Basic Blue. Sevron Blue Basic Blue 4. Sevron Blue BGL Basic Blue 35. Sevron Blue NF Basic Blue. Resolin Blue FBLD Disperse Blue 56. Se'vron Brilliant Red D Basic Red 19.

EXAMPLE I Ester interchange and polycondensation procedures were routinely conducted as follows:

A. Ethylene glycol and dimethylterephathalate in a molar ratio of approximately 2.5 to 1 based on the weight of dimethylterephthalate were placed in a stirred reactor. An ester interchange catalyst, manganese acetate, in a molar ratio of 0.03-0.05 was added. The vessel was purged with nitrogen gas and then heated gradually to 210- 220 C. for l-Vz to 4 hours.

During this time, methanol distilled from the reaction mixture and was collected. When the theoretical amount of methanol had been collected, the prepoly mer was heated for a few minutes at 215 220 C. to insure complete reaction. The hexaphenoxycyclotriphosphazene was then added.

B. The prepolymer of (A.) was then mixed with the polycondensation catalyst antimony oxide. This catalyst promotes the formation of high molecular weight polyesters. A phosphorus containing stabilizer such as trimethylphosphate can also be added at this time. The vessel is flushed with nitrogen gas and heated to 280 C. with stirring. The pressure was gradually reduced to 0.2 0.5 mm. of mercury. After l-%. to 3 hours, the vacuum was broken by admitting nitrogen gas and the polyester polymer allowed to cool. The polymer was then ground, dried and spun into 30/6 yarn. Two strands of this yarn were plied with one strand of 100 denier glass yarn and fabric knitted from the yarn. Limiting oxygen index values were then determined. The results are listed in Table 1.

The Limiting oxygen index (L01) is a method developed recently to measure the flammability of bulk polymers by C. P. Fenimore and F. J. Martin. (Modern Plastics, 45, No. 15, 141,146,148, 192, Nov., 1966). The method was later adapted to measure the flammability of textiles by G. C. Tesoro and C. H. Meiser, .lr. (Textile Res. J. 40, 430 436, May, 1970). The method provides a measure of the minimal volume fraction of oxygen in a slowly rising gaseous atmosphere capable of sustaining candlelike burning of the sample. For most materials, this value is independent of the physical form and dimensions of the sample over a broad range. In the present examples, the test was modified so that it would be applicable to thermoplastic fibers, such as polyester, which ordinarily tend to melt and drip when burned. 1n the present LOl teste, the polyester yarn is plied with 100 denier glass yarn and then knitted into test fabric. A very good and reproducible measure of the effectiveness ofa fire retardant additive can be obtained by noting the increase in the LO] value of the sample over that of the control containing no fire retardant. This increase is referred to as the 4 L01.

EXAMPLE 2 The process described in Example 1 was repeated on a pilot plant scale with the following change. Ten weight percent hexaphenoxycyclotriphosphazene was added at the beginning of ester interchange. The polymer had an l.V. of 0.67 and contained 8.7% flame retardant based on the phosphorus analysis.

The polymer was spun into yarn (1200/); one strand of this yarn was plied with one strand of 100 denier glass yarn and woven into fabric. L01 values were determined on the fabric and a L01 value of 0.037 was obtained. The yarn was bulked and tufted into 26 oz./yrd. shag carpet having a 1% inch pile height. This carpet was dyed with disperse dye using no carrier, Carolid 3F and Dysyn 813 carriers. The Carolid 3F carrier consists of biphenyl and 10% non-ionic emulsifier; it is supplied by Tantex Chemical Company.

The Dysyn 813 carrier is a self emulsifiable solvent carrier consisting predominantly of methyl naphthalene; it is available from Apex Chemical Company. The particular carrier selected is not critical and can be routinely varied. Dye uptake in each case was greater than that of the control and the dye lightfastness was equal to that of the control. Samples of the carpet were tested according to the Department of Commerce Standard titled The Surface Flammability of Carpets and Rugs, (Pill Test)," DOC-FF1-70. The results of this test are shown in Table 2.

TABLE 2 Pill Test Results of Carpet Containing 8.7% l-lexaphenoxycyclotriphosphazene Double backed Carpets of the same construction prepared from yarn of the same denier containing no phosphazene consistently failed the pill test.

EXAMPLE 3 The procedure described in Example 1 was repeated substituting octaphenoxycyclotetraphosphazene for the hexaphenoxycyclotriphosphazene. Yarn (30/6) was spun and plied with glass. LOl values were then determined on the knit fabric. A LOl of 0.255 and a 1L0l of 0.033 were found. The fabric was dyed along with a control with l% Foron Navy S-2GL* (C.l. Blue 79) and 1% Resolin Blue FBLD* (C.l. Disperse Blue 56).

The dye uptake was equal to or better than the control. The light stability for the Resolin Blue was equal to the control and that of the Foron Navy S-2GL was almost as good as the control. When a lighted match was applied to the yarn and removed, the yarn was selfextinguishing (i.e., a match test rating of 1). This is referred to subsequently as the match test".

EXAMPLE 4 Flame retardant polyethylene terephthalate was prepared using the procedure described in Example I. Instead of adding hexaphenoxycyclotriphosphazene at the end of ester interchange, 10 weight percent of the tetraphenyltetraphenoxycyclotetraphosphazene was v added at the end of the polycondensation. The polymer EXAMPLE 5 Three hundred grams of polyethylene terephthalate chips made by standard pilot plant procedure using techniques known to those skilled in the art, were placed in a resin kettle. The resin kettle was equipped with heater and stirrer and a bleed tube for nitrogen gas. The resin kettle was flushed thoroughly with nitrogen gas and then heated to 280C. to melt the polyester chips. Hexaphenylcyclotriphosphazene was then added and the mixture was stirred for a few minutes to mix the additive with the molten polyester. The polymer was then spun into 30/6 yarn. The procedure was repeated several times to produce yarn containing 4, 5, 6, 8, and weight percent of additive. These samples were subjected to a match test as previously. These results are summarized in Table 3.

TABLE 3 Match Test 7r Hcxaphenylcyclotriphosphazcne Match test ratings, when utilized in the present examples, are as follows:

1. Would not burn without support flame from match. 2. Self-extinguishing within 5 seconds after removal of match. 3. Burned longer than 5 seconds after removal of match. Three ends of yarn were plied with 100 denier glass fiber and knitted into fabric. LOl tests were then run on the knitted fabric. These are reported also in Table 4.

TABLE 4 Yarn (/6) EXAMPLE 6 The procedure of Example 5 was repeated substituting 10 weight percent of finely divided octaphenylcyclotetraphosphazene for the hexaphenylcyclotriphosphazene. A lighted match was applied to the extruded polymer fibers. When the match was removed, the fiber extinguished immediately (i.e., a match test rating of l).

EXAMPLE 7 The procedure of Example 5 was repeated substituting 10 weight percent of finely divided tris(2,2- dioxybiphenyl) cyclotriphosphazene. A lighted match was applied to the extruded polymer fibers. When the match was removed, the fibers extinguished immediately (Match test rating of 1).

It is understood that the preceding representative examples can be varied within the scope of this total specit'ication disclosure as it would be understood and practiced by one skilled in the art with a minimum of routine experimentation.

What is claimed is:

1. Flame retarded linear polyester containing from about 2* to about 20 weight percent of a thermally and chemically stable cyclophosphazene derivative selected from the group consisting of cyclotriand cyclotetraphosphazene, having, respectively, 6 or 8 substituents thereon selected from the group consisting of phenyl and phenoxy as flame retardant, said cyclophosphazene thermal and chemical stability being maintained at temperatures up to about 300 C.

2. Flame retarded polyester according to claim 1 wherein said cyclophosphazene is present in an amount of from about 5 to about weight percent.

3. Flame retarded polyester filament containing from about 1 to about 20 weight percent of a thermally and chemically stable cyclophosphazene derivative selected from the group consisting of cyclotriand cyclotetraphosphazene having, respectively, 6 or 8 substituents thereon selected from the group consisting of phenyl and phenoxy as flame retardant, said cyclophosphazene thermal and chemical stability being maintained at temperatures up to about 300 C.

4. Flame retarded polyester filament according to claim 3 wherein said cyclophosphazene is present in an amount of from about to about 10 weight percent.

5. Flame retarded linear polyester containing from about 1 to about 20 weight percent of hexaphenoxycyclotriphosphazene as flame retardant, said cyclophosphazene thermal and chemical stability being maintained at temperatures up to about 300 C.

6. Flame retarded polyester according to claim 4 wherein said flame retardant is present in an amount from about 5 to about 10 weight percent.

7. Flame retarded polyester filament containing from about 1 to about 20 weight percent of hexaphenoxycyclotriphosphazene as flame retarded, said cyclophosphazene thermal and chemical stability being maintained at temperatures up to about 300 C.

8. Flame retarded polyester filament according to claim 7 wherein said flame retardant is present in an amount from about 5 to about 10 weight percent. 

1. FLAME RETARDED LINEAR POLYESTER CONTAINING FROM ABOUT 1 TO ABOUT 20 WEIGHT PERCENT OF A THERMALLY AND CHEMICALLY STABLE CYCLOPHOSPHAZENE DERIVATIVE SELECTED FROM THE GROUP CONSISTING OF CYCLOTRI- AND CYCLOTETRAPHOSPHAZENE, HAVING, RESPECTIVELY, 6 OR 8 SUBSTITUENTS THEREON SELECTED FROM THE GROUP CONSISTING OF PHENYL AND PHENOXY AS FLAME RETARDANT, SAID CYCLOPHOSPHAZENE THERMAL AND CHEMICAL STABILITY BEING MAINTAINED AT TEMPERATURES UP TO ABOUT 300*C.
 2. Flame retarded polyester according to claim 1 wherein said cyclophosphazene is present in an amount of from about 5 to about 10 weight percent.
 3. Flame retarded polyester filament containing from about 1 to about 20 weight percent of a thermally and chemically stable cyclophosphazene derivative selected from the group consisting of cyclotri- and cyclotetraphosphazene having, respectively, 6 or 8 substituents thereon selected from the group consisting of phenyl and phenoxy as flame retardant, said cyclophosphazene thermal and chemical stability being maintained at temperatures up to about 300* C.
 4. Flame retarded polyester filament according to claim 3 wherein said cyclophosphazene is present in an amount of from about 5 to about 10 weight percent.
 5. Flame retarded linear polyester containing from about 1 to about 20 weight percent of hexaphenoxycyclotriphosphazene as flame retardant, said cyclophOsphazene thermal and chemical stability being maintained at temperatures up to about 300* C.
 6. Flame retarded polyester according to claim 4 wherein said flame retardant is present in an amount from about 5 to about 10 weight percent.
 7. Flame retarded polyester filament containing from about 1 to about 20 weight percent of hexaphenoxycyclotriphosphazene as flame retarded, said cyclophosphazene thermal and chemical stability being maintained at temperatures up to about 300* C.
 8. Flame retarded polyester filament according to claim 7 wherein said flame retardant is present in an amount from about 5 to about 10 weight percent. 